1. Field of the Invention
This invention relates to display assemblies and more particularly to structures and addressing techniques for display assemblies using liquid crystals and the like.
2. Description of the Prior Art
The use of electroluminescent panels as display media is well developed. More recently, light emitting diodes, liquid crystals and plasma panels have been used for the presentation of matrix type displays. In general, a large number of input electrodes and switching positions are used in the prior art in order to address discrete points and achieve reasonably high resolution. A common method of implementing activation of selected elements within a matrix, for example, includes the use of orthogonal grid leads to form the matrix and separate switching controls for applying a potential to each grid lead. Using such an arrangement, a unit of 256 elements or cross points would be arranged in a matrix of 16 .times. 16 and 32 switching or driving elements would be required. For a 1024 .times. 1024 array of 1,048,576 discrete points, as many as 2,048 leads and drivers are required, in addition to the necessary selection circuitry.
Various attempts have been made to reduce the number of leads and active drivers required to achieve a particular degree of resolution. Two approaches of particular interest are an electron beam display and a digitally addressed solid state electroluminescent device. In each of these systems, an approach to a theoretical minimum of active elements has been indicated. In the first instance an evacuated envelope, a complicated cathode assembly, and a multitude of apertured multiplier plates are required. In the second instance, a special photo conductor pattern is required which is difficult to construct and select. Still other attempts to circumvent the need for a multiplicity of leads, employ glow transfer mechanisms and schemes devised for plasma panels.
The term matrix may be more generally applied to cover the definition of cross points or areas by means of intersecting or physically proximate conductors which can be individually stimulated to establish a discrete condition at any selected area. Thus, the field of interest includes digital clocks and data display panels using active elements such as liquid crystals, gas, plasma, light emitting diodes, and ferroelectric materials. A common assembly of elements includes a layered panel, or panels, having configured conductors on opposing faces or connected to specially configured active elements. The conductors are selectively energized to modify the characteristics of the active elements and thereby create the desired display.